Refrigerant Pressure Sensor / Switch: Description and Operation
A/C PRESSURE SENSORA/C Pressure Sensor:
The Air Conditioning (A/C) pressure sensor is located in the A/C high side pressure refrigerant line in front of the air box. The pressure sensor is a transducer that varies resistance according to changes in high side refrigerant pressure. The PCM measures the signal voltage from the A/C pressure sensor, which is a reduced value of the PCM 5-volt reference. The maximum voltage ranges of the sensor are around 0.1 volts at 0 psi to 4.9 volts at 459 psi. The sensor input is used primarily by the PCM to determine when and what speed to turn the cooling fans On. It is also used to turn Off the A/C relay if the system pressure is not within 180 - 2999 kPa (26-435) psi. The sensor input also aids in determining Idle Air Control (IAC) position for idle speed during A/C operation.